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4D Imaging of Protein Aggregation in Live Cells
08:59

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Published on: April 5, 2013

Proinsulin maturation, misfolding, and proteotoxicity.

Ming Liu1, Israel Hodish, Christopher J Rhodes

  • 1Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical Center, Ann Arbor, MI 48109, USA.

Proceedings of the National Academy of Sciences of the United States of America
|September 28, 2007
PubMed
Summary

Misfolded proinsulin (PI) traps normal PI, reducing insulin production and causing beta cell death. This PI misfolding is a key step in the development and progression of diabetes.

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Area of Science:

  • Endocrinology
  • Molecular Biology
  • Cell Biology

Background:

  • Proinsulin (PI) is a precursor to insulin, crucial for glucose regulation.
  • Defects in PI processing and trafficking are implicated in diabetes pathogenesis.
  • Understanding PI behavior is vital for developing diabetes therapies.

Purpose of the Study:

  • To investigate the molecular mechanisms of proinsulin (PI) trafficking and processing.
  • To identify the role of PI misfolding in the development of diabetes.
  • To explore the interaction between mutant and non-mutant PI in beta cells.

Main Methods:

  • Constructed a human PI cDNA fused with GFP to track PI.
  • Expressed mutant PI in Akita mice to study diabetes development.
  • Analyzed protein complexes and PI trafficking in beta cells.

Main Results:

  • The hProCpepGFP chimera was processed and cosecreted with insulin.
  • C(A7)Y mutant PI caused autosomal dominant diabetes in Akita mice.
  • Misfolded PI formed complexes with non-mutant PI, impairing trafficking and reducing insulin production, leading to beta cell loss.

Conclusions:

  • Proinsulin (PI) misfolding disrupts endoplasmic reticulum exit of non-mutant PI.
  • This trapping mechanism initiates beta cell dysfunction and demise.
  • PI misfolding is a critical early event in diabetes onset and progression.